Inciting Event: Hopeful Boston state police cadet Billy reluctantly agrees to go undercover, starting with a prison stint to gain street cred. Meanwhile, the seemingly all-American Colin—who has been groomed since boyhood by mafia boss Frank Costello—is given a cushy job as a plains-clothes detective.
Three things worth noting here:
1) The plot lines’ of both characters are neatly grouped together to keep the structure tight.
2) Note how reluctant Billy is to go undercover. He is essentially “rejecting” the Call to Adventure—mentally if not physically—which is just as it should be.
3) This is a great example of the Inciting Event being the turning point halfway through the First Act (instead of the first scene, as people sometimes mistakenly believe it is). Up to this point, viewers don’t even have a clue what’s going on or how the unfolding setup will create a story. Then, bang, the Inciting Event happens, and it all becomes clear.
First Plot Point: Now out of jail, Billy manages to get Frank’s attention and become a member of his organization. Billy is the main character, and he carries the weight of the structure. But we also have a nice tie-in with Colin’s character, as this is the first time we see him phoning “Dad” and feeding Costello information from the cops.
First Pinch Point: Billy learns there’s a mole in the cops, and Colin learns there’s an undercover informant among Frank’s guys. Basically: they learn about each other’s existence. Their mutual discoveries are framed around a handoff between Frank and the Chinese mafia.
Midpoint: The major moment of revelation in the middle of the movie is Billy’s discovery that Frank is working as an FBI informant—which allows Frank to operate with legal immunity. However, we also have other important shifts going on as Frank brings the heat down on Colin, and Billy’s handlers—Captain Queenan and Sergeant Dignam—threaten him into towing the line as well. It’s interesting to note that, really, Frank is the main antagonist to both Billy (obviously) and his own man Colin (not so obviously), much more than Billy and Colin are to each other.
Second Pinch Point: After being forced to write out his identifying numbers so Frank can pass them to Colin, Billy follows the papers—in an envelope marked “Citizens’ Trust”—and nearly catches Colin. Colin accidentally kills a passer-by, but he also captures a photo of Billy on a traffic camera. Subsequently, a drunken Frank threatens Billy—seemingly suspecting him of being the rat.
Third Plot Point: Colin—who has ironically been given the job of identifying the mole in the police (himself)—puts a tail on Captain Queenan and follows him to a meeting with Billy. Colin then alerts Frank’s men to the location. Billy escapes, but Queenan is thrown off the building and dies. Billy barely manages to keep his cover. This completely shakes up the plot. Queenan’s death a major blow to both Billy and Colin (who never intended Queenan to die) that pushes them both to the brink.
Climax: After killing Frank in a raid (because he believed Frank was going to hand him over to the FBI), Colin returns to the station to find Billy waiting for him. Billy wants to get paid and leave the force. While Colin is working on the necessary papers, Billy recognizes the “Citizens’ Trust” papers on Colin’s desk—and realizes he’s the mole. From this point on, the confrontation is mano a mano between Billy and Colin.
Climactic Moment: After arresting Colin, Billy is shot and killed by Colin’s partner—who was also, unbeknownst to Colin, a mole for Frank. Colin then kills his partner, leaving only himself standing to tell what’s happened. We actually have two Climactic Moments in this story, one for each of its main characters. But since Billy is the protagonist, and because the conflict between him and Colin ends with his death, this is the moment when the story’s tension balloon is pricked.
Resolution: Colin recommends Billy for a posthumous Medal of Merit. Colin’s girlfriend—who was also Billy’s psychologist—rejects him, having learned the truth from Billy. She presumably opens a letter Billy had given her, telling her what steps to take after his death. Colin returns to his apartment and finds Sergeant Dignam waiting for him. Dignam kills him and leaves—effectively tying off all the story’s major loose ends.
